One type of assembled commutator comprises a plastic base supporting a plurality of segments. The segments are form locked to the base, for example by providing tongues on the segments which are received in recesses in the base. Each segment has a tang which extends radially outwards and has a U-shaped portion which may be supported by a collar at one end of the base. To connect an armature coil to the segment, the coil wire is wrapped into the base of the U-shape which is then collapsed onto the wire and heated in a hot forging or resistance welding process to burn off the insulation covering on the wire and form an electrical and mechanical connection with the wire. The segments are usually slid axially onto the base, in the direction of the collar.
In many applications the electric motors are subject to high G-forces, particularly in motor vehicles where there is often rapid acceleration and deceleration. This may result in axial movement of the segments on the commutator base, which may place a strain on the connection between the segment and the armature winding as well as upsetting the geometry of the commutator.